In <36ae4e37.799103 at news.zedat.fu-berlin.de> cijadra at zedat.fu-berlin.de
(Cijadrachon) writes:
>>(To certain people: Skip apart from last sentence.)
>>>>But you better ask someone else for that, F.Frank LeFever, Ph.D.
>>>might have some theories about memory systems.
>>Sorry, I couldn't resist.
>>>Generally speaking, "visual"
>Apart from that I know that there is seeing and "seeing", why do you
>use " "?
Had to go back to my original post to get the context. Put the word in
quotation marks simply to make salient its apposition to "non-verbal"
in that statement, i.e. to make the point that people somewhat
carelessly equate the two in the context of classsifying memory
systems/phenomena.
>>information takes many parallel paths from primary visual cortex to
other brain areas, and the different paths are
>>encoding different aspects of visual input.
>Wouldn't mind the long version on that, either.
The long version is VERY long. I have bits and pieces in various
articles on different aspects, scatterd in my files, but perhaps
someone can post a good review (probably one in recent volume of Annual
Review of Neuroscience).
>>Many years ago, Mortimer Mishkin and colleagues began to indentify a
"dorsal stream", which
>>carried (primarily? only?) information about the location of visual
>>objects in space, and a "ventral stream" which carried (primarily?
>>only?) information about object identity: hence "where" and "what"
>>visual information.
>Question marked theories?
I put question marks because "what" and "where" are convenient
short-hand terms for working classification based on complex data;
until these and future data are better analysed it is uncertain whether
we can simplify and say that only "where" information is carried in the
dorsal stream and only "what" information in the ventral stream. One
might want to be more cautious and say data so far say these are what
these streams PRIMARILY carry, but there may be some kinds of
information carried in these two streams which do not fit so neatly
into these classifications.
For example, a patient of mine with prosopagnosia (defect in ventral
stream, probably near terminus in hippocampus?) was, after acute stage
of recovery, quite good in memory for SOME kinds of
non-representational forms; based on intact dorsal stream? or based on
intact portion of ventral stream? "non-spatial" aspects of visual FORM
information?
Are all aspects of object identity carried in ventral stream? e.g.
visual texture, color? Is it just a matter of recognition of objects
in multiple spatial orientations as opposed to a specific orientation?
etc., etc.
>>Talking about which (or should I say "what"s?), if a company with red
>cans and white writing is imitating Coca Cola or if playing the cloud
>game of making them into sheep or mountains and pulling wrong
>"identifier cards", where in the brain is that?
>I know nearly nothing about the temporal cortex. Is there anything in
>there to do with such?
Not sure what you are asking here. Maybe this is relevant: current
thinking is that temporal lobe (medial part, particulary hippocampus
and adjacent cortex) is needed for formation of memories, but is not
site of "storage". Possibly you are asking about usual activation of
sites in (e.g.) parietal association cortex which may recapituulate
some of the original pattern of excitation; if activated in unusual
way, person may not discriminate true from false memories, or memory
from current experience (e.g. as in hallucinations? acid trips?).
>>> They were exploring memory systems and were
>>particularly interested in tracing these two streams to the
>>hippocampus.
>How does data go from the occipital cortex to me?
I don't know. Not clear just where you're at.
(American English play on words...)
But seriously, folks (oblique reference to American comedian): the
question of where "the person who experiences all this" is invites
opening a can of worms. We can follow the trail from retina to lateral
geniculate to occipital cortex (ignoring side-roads along the way) to
these "streams" in posterior association cortex to hippocampus, but it
is not clear how far one must go along this route or what side-roads
must be included to achieve the personal experience we talk about when
we say "I saw that".
Some food for thought: poor HM (famous patient with bilateral temporal
lobe ablation) cannot form memories lasting more than a few minutes,
but is of course quite capable of saying "I saw that" when he is shown
something. On the oother hand, Larry Weiskranz (and Eliz. Warrington,
my speaker at NYAS last November) have shown that people with "cortical
blindness" (lesion very early in occipital part of route) can to some
extent guide their movements visually (i.e. locate visual targets with
better than chance accuracy) without the experience of seeing them.
>>>Maybe I should be more explicit: in dorsal and ventral areas of
>>so-called "association cortex" in (occipito-)parietal lobe.
>I do not know dorsal and ventral.
>If I put one hand sideways (thumbs downwards) outside over the
>occipital cortex and the other over the parietal one
>then how deep inside from there?
Dorsal and ventral refer to directions/locations better seen in
organisms with CNS laid out in more of a straight line: dorsal on the
back side, ventral on the belly side. In humans, with upright posture
and many kinks and folds, takes a little more effort to see these
directional referents.
(1)dorsal in this case is "above", for a person sitting or standing
upright; ventral "below"; but both streams are aimed at and converge in
temporal lobe, down near the ears.
(2) not deep at all: these are streams within the cortex, which is very
thin (about the same in a rat as in a human: 2-4 mm??).
>>>... abstract in J.
>Is J. journal or what does it mean?
>> of the International Neuropsychological Society
Yes; J. = Journal
>>>... for those interested in fMRI of cognitive function, check out
www.nyas.org
>(Currently can't access the internet.)
Too bad. You'd get a lot more info than you can get from newsgroups.
>>"Too lazy to cognito, ergo sum" ... but it can't mean thinking because
>the Westie branches never got that the sequencer and oneself can
>think.
>Been wondering for a while what cognitive means?
Not well-defined, but in common usage refers to such things as
"thinking" "remembering", etc.
Bytheway: still don't have ref. to my own comments on Mishkin (incl.
some speculations of memory vs. hallucination question), but did find
recent article on fMRI of "what" and "where" systems I referred to:
Mecklinger, A. (1998) Neuropsychologia, 36, 441-460.
(he's from Max-Planck-Inst., Leipzig)
F. LeFever
>>>F. Frank LeFever, Ph.D.
>>New York Neuropsycholgy Group
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